I just finished with the feat plan for a Gendarme Cavalier. The archetype gives several bonus feats from a list, but it doesn't say whether or not you have to qualify to take them. I made the plan on the assumption that I do have to qualify.

1: Steadfast Personality: Can use Cha instead of Wis for Will saves against Mind-Affecting effects.
1: Animal Affinity: +2 to Ride and Handle Animal. +4 at ten ranks.
1: Power Attack
2: Mounted Combat: If your mount is attacked, as an immediate action you can do a Ride check to negate.
3: Ride-By Attack: When mounted and charging, you may make the attack at any point during the charge. Does not provoke.
5: Wheeling Charge: When mounted and charging, you may make a single turn up to 90 degrees as long as you move min. 10 feet before and after. Allies donít impede the charge.
5: Spirited Charge: When mounted and charging, deal double damage with a melee weapon. Triple with a lance.
7: Indomitable Mount: Once per round, immediate action, if mount needs to make a saving throw, can make a Ride check instead.
8: Improved Bull Rush
9: Dodge
11: Trample: When making an overrun attempt while mounted, target canít avoid you. If successful, mount can make a hoof attack against target with the +4 Atk bonus for prone targets.
11: Unseat
13: Mobility
14: Spring Attack
15: Trick Riding: Wearing light or no armor, donít need to make Ride checks for anything DC 15 or lower. Can use benefits of Mounted Combat twice a round.
17: Mounted Skirmisher: If mount moves its speed or less, can still make full-attack.
17: Shield Focus: +1 shield AC.
19: Mounted Shield: Can add shield bonus (not including enhancements) to mountís AC and to Ride checks using Mounted Combat.
20: Mounted Blade: Upon successful attack using Ride-By, may attack target adjacent to first one. -5 Atk and no benefits from a charge for this attack.

When I play her, I will ask the GM about needing to qualify for the bonus feats. If he says I don't, then I'll remove Mobility and move everything up a slot. Except for Spring Attack since it has to be a bonus feat without Mobility. I might also remove Dodge and Shield Focus and figure out something more useful.

I'm going to give the horse the Charger archetype, giving it Power Attack, Improved Overrun, and Charge Through.

If it doens't say you get to ignore pre-req's, it's usually assumed you must meet them. You receive 7 bonus feats by level 20 and there are 7 to choose from. Although this does translate into if you choose some of the feats as character level feats and get all 7, you will open up the choice to receive combat feats. So what I would do if I were you, is take every feat you get from character level feats as those seven.

So as first level, you could take mounted combat as character level feat and ride by attack as bonus feat at level 1. Then at levels 3 and 5 you get two more, plus a bonus at 5th. so that'd be five of them already. So then at 7th level, you take one more, plus your bonus feat at 8th, wham you have all 7!!.

Now, for your bonus feats, you can take any combat feat ya want!! lol

That's what I would do. IF you wanted combat feats available to as much as possible. That's your fastest option. Because unfortunately, you don't receive the specific that you get to ignore pre-req's, like a monk does. But for a cavalier on horseback to have all them feats, that's a mountain of armor n weapons comin' down on yer opponents like an avalanche. lol

The reason I didn't take Mounted Combat at level one is because the Order of the Saddle gives it as a bonus at level two. And unlike the archetype, it has no text to say I could take something different. So I would either have the feat twice or retrain.